Method for continuously washing coal ash under coal bed methane well in bride type without causing pollution

Abstract

The invention relates to a method for continuously washing coal ash under a coal bed methane exploiting well in a bride type without causing pollution, comprising the following steps: putting process oil pipe columns which are used for continuously washing the coal ash under the coal bed methane exploiting well in a bride type without causing pollution into an oil well casing; packing an upper packer and a lower packer; washing a coal ash surface at the bottom of the coal bed methane well, making injected water enter an oil sleeve annular space and jet out of a nozzle to damage the coal ash surface and causing the coal ash to return to the ground surface together with flowback water; unpacking the upper packer and the lower packer, stopping a pump, lifting the process oil pipe columns and deblocking all the oil pipe columns. The invention has the advantages that the coal layer is packaged and the channels of the injected water and the flowback water are changed to form a sealed hydraulic circulating space in oil pipes, the sealed hydraulic circulating space can be matched with the oil pipe columns to form a set of working pipe columns which are convenient to butt, do not need to be demounted repeatedly and are capable of continuously washing the coal ash under the coal bed methane well, and the washing and the pollution of the injected water or the flowback water to the coal layer are effectively avoided.

Description

technical field [0001] The invention relates to the technical field of coal bed gas exploitation. In particular, it relates to a downhole pipe string of a coal bed gas well and a method for continuously flushing coal ash. The downhole pipe string is a special tool for flushing coal powder downhole; the method of flushing coal dust is to use fluid splitting to form a hydraulic or gas closed cycle in the pipe to flush sand and coal powder. Background technique [0002] At present, in the process of coalbed methane development, the pulverized coal is continuously carried out with the drainage and depressurization process, and the pulverized coal is produced with the water, but the water cannot carry all the pulverized coal out, and a large amount of pulverized coal will accumulate in the pockets of wells with serious ash production. The method of flushing coal powder and the method of fishing for coal powder are mainly used to remove coal dust accumulated in pockets at the bot...

AI Technical Summary

Problems solved by technology

Disadvantages of this pulverized coal fishing process: firstly, it is necessary to lower the pipe string repeatedly, and for wells with serious coal pulverized accumulation, this process is time-consuming and costly; Put down the vacuum-type tube for oil extraction, and the downhole sand dredging string hits the pulverized coal surface, causing friction between the string and the well wall. It is not suitable to use the pulverized coal method to remove the pulverized coal accumulated in the pocket at the bottom of the well in a highly inclined well

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